The first tool is mostly for educational purposes, providing a graphical user interface that shows the internal data structure of .PST files, according to Daniel Ko, a Microsoft Outlook development manager, in a Microsoft-produced video. The second tool, File Format SDK, provides a library of source code and high-level APIs that developers can use to build their own applications.

The SDK can be used to support data migration scenarios to move .PST files from one platform to another, according to Ko. It can also help facilitate searches for particular content in the .PST files, such as might be used in e-discovery software for legal purposes. Ko also explained that developers could use the SDK to check outbound e-mail content, such as might be used in corporate compliance software. He also drew a whiteboard sketch showing how photos saved in the .PST file format could be extracted and used for a cloud-based photo album, or some other type of application.

The kit currently lets developers read the data in a .PST file. However, Microsoft is working on a capability in the kit that would enable writing to .PST files too, according to Ko.

In essence, the tools will better enable third-party software developers to build e-discovery and data migration solutions for use with Outlook, according to Sheri McLeish, an information and knowledge management analyst at Forrester Research.

"What they're enabling is easier access to those [.PST] files to scan them for issues around e-discovery potentially, or to migrate or move them to other new hardware devices or locations," McLeish said by phone. "So it's really an enabler and a continuing effort on the part of Microsoft to make that [.PST file format] more portable and open."

Microsoft decided to release these two tools to supplement about 200 pages of documentation on the .PST file format that the company has already released as part of its "open specification promise." This initiative, announced in February of 2008, opens up the documentation of file formats and APIs used with a number of Microsoft's applications. According to William Kennedy, Microsoft's corporate vice president for Office communications and forms, Microsoft has published more than 33,000 pages of these technical documents, which help third-party developers interoperate with Microsoft's products.

"While the .pst file format previously required a Microsoft Outlook license to access, the documentation and tools obviate that need, enabling greater interoperability with the data than ever before," Kennedy, explained in a Microsoft blog.

The SDK adds to existing developer tools. Previously, developers had access to the data in a .PST file through the "Messaging Application Programming Interface and the Outlook Object Model," according to Microsoft's announcement.

The new tools will help Microsoft's partners as well as its competitors. However, Microsoft benefits too because the tools will aid migrations to different Office versions, McLeish said.